Cellular phone accessory market is a well established market with several kinds of accessories available to enhance user experience. Accessories can be wired or wireless or available as attachments. Some examples of commonly available accessories are headset, keyboard, speakerphone, camera and display. A cellular phone accessory is defined to be a device that is controlled by the cellular phone and either extends or partitions existing functionality into an easy to use device. This implies that there exist a master slave relationship between a cellular phone and an accessory wherein cellular phone is master and accessory is slave.
In some situations a cellular phone gets used as a slave and other devices such as a personal computer (PC) control the cellular phone. In these cases the master slave relationship is reversed and a cellular phone gets used as a slave and serves as a data modem. In this setup where a cellular phone is used as a data modem, cellular phone is termed as mobile termination equipment (MT) and personal computer that controls cellular phone is termed as terminal equipment (TE).
This MT/TE relation enables any data oriented service to be available to a user using a cellular network since a cellular phone acts as a cellular gateway to internet protocol network. In particular real time interactive applications using internet protocol multimedia subsystem (IMS) can also be supported.
Thus it is to be noted that a cellular phone accessory extends existing cellular phone functionality in hardware, whereas a cellular phone used as a data modem extends functionality in software with new IMS applications that can be executed on terminal equipment. A software functionality extension using MT/TE relation serves cellular phones that do not have ability to run new software, whereas a cellular phone accessory device serves cellular phones with limited hardware features. So both relations serve a useful purpose, but each is offered as a different device combination. That is, to have extended hardware functionality and extended software functionality, a person would have to carry a cellular phone, a cellular phone accessory device and terminal equipment resulting in a total of three devices.
Hence a user would have to carry three devices if there is a need for both hardware and software functionality extension, which is not a preferable solution by most users.
To alleviate this problem, that a user would have to carry three devices, a cellular phone that is programmable could be used instead of a non-programmable cellular phone. Such programmable phones exist in market but are available in very low volume and very expensive compared to low end and middle range phones. This is due to the fact that low end and middle range phones use application specific integrated circuits to reduce power usage and bill of materials whereas completely programmable phones have to offer sophisticated operating systems and corresponding extended set of bill of materials.
Cellular phones are categorized into low end, middle range and high end phones also called smart phones. Only high end phones support general purpose programmability. General purpose programmability provides a programmable platform to support both real time interactive and non-interactive multimedia applications. There are several design challenges to provide complete general purpose programmability even in high end programmable smart phones. A list of challenges is given below.                a) Smart phone market is fragmented with different programming environments, or operating systems, and hence making it difficult for application vendors to produce mass market solutions reusable in a wide range of smart phones.        b) Smart phones are designed with several different chipsets, architectures and corresponding interfaces making it difficult for software solutions to expect similar functionality on different brands of smart phones.        c) Smart phone market is extremely low volume in comparison to low end and middle range phones. Smart phone market is currently estimated to be less than six percent of overall global cellular phone market place. Hence there are minimal development tools available as compared with tools that are available to develop applications for a personal computer.        d) Smart phones usually consume more power due to general purpose processor executing several millions of instructions in software.        e) Smart phones require more memory than conventional low end and middle range phones.        f) Due to the number of extra components, smart phones are usually bigger and heavier thereby affecting the usability of a cellular phone dramatically.        g) Interactive multimedia applications are difficult to program due to nonstandard interfaces to digital signal processing (DSP) unit.        
Hence it can be seen that offering new functionality through smart phones although technically feasible, is not a viable business solution due to its low volume and fragmented programming environment.
For high volume, it is necessary that a solution that offers both hardware and software extension work with low and middle range phones.
Low end phones are not programmable and middle range phones offer minimal programmability with downloadable software using Sun Microsystems Java 2 Micro Edition (J2ME) or Qualcomm BREW environments. In particular IMS applications require interfaces to digital signal processing unit to get access to encoded multimedia bits. This is not provided in either low end or middle range phones.
Thus neither smart phone solutions nor a low end or middle range phone solutions can offer extended set of hardware and software functionality without compromising the business case of leveraging high volumes of low end and middle range phones.
Hence it can be seen that a device that can offer hardware extension as a cellular phone accessory device and software extension for real time interactive multimedia programmability will solve the above mentioned three device problem while leveraging mass market penetration of low and middle range phones.
This device of present invention is a combination of a cellular phone accessory functionality and terminal equipment programmability to support real time interactive multimedia applications. A device that is a cellular phone accessory provides hardware extension, and a device that behaves as a TE is also programmable. Hence such a combination of a cellular phone accessory and terminal equipment would solve both problems including lack of real time interactive multimedia programmability of low to middle range phones and limited market penetration of smart phones.
The combination device is achieved by incorporating real time interactive multimedia functionality as described in internet IMS specifications from standards body third generation partnership project (3GPP) into a cellular phone accessory device. IMS specifications prescribe an IMS client and an IMS server that interoperate to provide real time interactive multimedia applications. Hence a device that is both a cellular phone accessory and an IMS client will enable new real time interactive multimedia applications while working with low end and middle range phones. This device shall be referred to as IMS accessory device henceforth.
IMS accessory device is unique and is not known to exist in prior art. This will become very evident by the following description about prior art.
The prior art description is structured as follows: first functional description of prior art IMS client is covered; second functional description of cellular phones and challenges in enabling real time interactive multimedia services in cellular phones are described; finally the inadequacy of existing solutions for enabling real time interactive multimedia services on low end and middle range phones is described.
FIG. 1 shows the prior art IMS client 31, which is grouped into two functional components, namely IMS client control and protocol components 32 (or IMS control) and IMS client media components 33 (or IMS media). IMS control 32 is typically hosted by general purpose processor (GPP) 34 and IMS media 33 is hosted by digital signal processor (DSP) 35.
FIG. 2 shows a prior art low end phone 36 functional architecture.
There are several issues to resolve before IMS services can be made available on low end phone 36.                a) Processing power and memory issue on microcontroller unit (MCU): There may not be enough processing power and memory available for hosting IMS control 32 in low end phone microcontroller unit 37.        b) Processing power and memory issue on DSP: Low end cellular phones 36 may not have enough processing power available in digital baseband DSP 38 to simultaneously run two and half generation cellular packet switching protocol stack such as general packet radio service (GPRS) and vocoder. This is mandatory to support real time interactive multimedia services.        c) Streaming Vocoder access: MCU DSP link 39 is limited to exchanging data that is non-real time like phone call control signaling, wireless application protocol (WAP) data and hence real time stream support for voice is not available. Streaming vocoder access is mandatory to support real time interactive multimedia services.        d) Porting issue: In low end phones 36, MCU 37 runs proprietary embedded operating systems. Hardware and operating systems differences introduces several challenges, such as sixteen bit versus thirty two bit architecture, little-endian versus big-endian, availability of complete transport control protocol/internet protocol (TCP/IP) stack, access to persistence storage, lack of uniform memory management policies, nonuniform support for programming language like C or C++ for example runtime C libraries, string libraries, suitable application programming interface (API) to audio layer or vocoder layer, lack of uniform APIs for power management layer, APIs for networking connection management, lack of uniform APIs for window system management, lack of uniform APIs address book and recent call list. These challenges significantly increase the cost and time for building IMS services on low end cellular phones 36.        
FIG. 3 shows functional architecture of middle range phone 40. Except for few differences like additional multimedia coprocessor 41, middle range phone 40 shares several identical components with 36 and also shares all the limitations of low end phones 36 described above as far as supporting real time interactive multimedia services. It is important to note that even with addition of multimedia coprocessor 41, multimedia data flow 42 does not support real time streaming which is needed for supporting real time interactive multimedia services.
FIG. 4 shows the functional architecture for high end phone 43. The general purpose processor (GPP) 44 and multimedia coprocessor 45 have higher processing power than its middle range phone 40 counter parts. GPP GPP-DSP bridge or DSP bridge 46 provides high performance streaming support for multimedia data and hence multimedia flow 42 supports real time multimedia streaming. Due to these differences, high end phones 43 can support real time interactive multimedia services.
One way to overcome the limitations described for low end phones 36 and middle range phones 40, is to build new features and functionality into cellular phone accessory that can interoperate with low end phones 36 and middle range phones 40. These accessories themselves can add features requiring no changes to major changes to software and/or hardware components in the cellular phones. Hence an ideal IMS accessory should provide IMS client 31 functionality without calling for any changes to software and hardware components in the cellular phones in order to interoperate with widest range of low end phones 36 and middle range phones 40.
US Doc 20020068600 proposes a mobile video phone system comprising a mobile telephone device, wearable radio communication device with display and an optional radio headset. It primarily addresses the ease of use issue of video telephony. The mobile telephone device co-ordinates the exchange of images/video between remote user and wearable radio communication device with display. Also, the mobile telephone device co-ordinates the exchange of voice between remote user and radio headset. This system does not provide IMS client functionality and hence does not support real time interactive IP multimedia services and additionally this system calls for moderate to significant software changes in the mobile telephone device.
U.S. Pat. No. 6,768,911 proposes a mobile communication terminal device consisting of mobile communication device with detachable display and ear phone component. The communication device and the components communicate using short-distance radio technology bluetooth. This prior art primarily addresses the size and portability of the device while maintaining rich functionality. This system does not provide IMS client functionality and hence does not support real time interactive multimedia services and additionally does not provide interoperability with existing low end and middle range phones.
U.S. Pat. No. 6,731,951 shows a cellular device having two parts, one having cellular communication support and bluetooth link, that can be stored away or used as a modem with PC or can work with the second component which is having input and output device (display, keyboard), camera and a bluetooth link. Obvious advantage being that the second device is small, easy to carry, small size battery and first unit being not close to the body, better signal strength for cellular connection and hence better battery life. This system does not provide IMS client functionality and hence does not support real time interactive multimedia services. Also the system calls for significant hardware and software changes to existing phones to interoperate.
U.S. Pat. No. 5,590,417 proposes a detachable headset device as an accessory to a cellular phone. The detachable headset when attached to phone can function as a speaker and microphone. The headset can also be detached and placed on the head of the user. In this mode of operation, the headset and the cellular phone communicate using low power RF transceivers. This system does not provide IMS client functionality and hence does not support real time interactive multimedia services.
U.S. Pat. No. 6,788,332 introduces a digital camera with wireless link that can operate with Personal digital assistant (PDA) or cellular phone to communicate with images or facsimiles to a remote user by setting by data call. This system does not offer real time interactive multimedia services.
Some prior art systems provide additional features and services by using PC and PDA as TE programmed with new functionality and simply treating the cellular phone as modem or MT. These systems implement IMS client functionality by splitting the implementation between cellular phone or MT and PC and PDA or TE. For interoperability with widest range of low end and middle range phones, the functional split should call for no changes in cellular phone or MT. Additionally, the ideal solution will implement IMS client functionality as a TE and also function as an accessory such as hands free phone or headset or viewer to the cellular phone for at most convenience to the end user.
US Doc 20030210678 proposes a method for connecting TE to IMS server using a cellular phone as MT. This method calls for functional split in implementing IMS client functionality between TE and MT. As per the method proposed in this prior art, terminal equipment performs protocol stream functions including real time transport protocol (RTP) and real time transport control protocol (RTCP) functions. The MT performs IMS proxy functions such as identification or authentication functions, as well as call control functions. Implementing IMS proxy function in mobile terminal limits the terminal equipment interoperability to selected mobile terminals that support IMS proxy function. Additionally, this solution does not combine terminal equipment function with cellular phone accessory function for end user convenience.
U.S. Pat. No. 6,788,676 proposes user equipment that includes a MT coupled to a TE. The TE includes IMS proxy adjunct which implements extensions needed in session initiation protocol (SIP) and session description protocol (SDP) for connectivity to IMS server. The user agent (UA) running on TE uses IMS proxy adjunct for accessing IMS services. Additionally, IMS proxy adjunct also implements support for quality of service (QoS) between TE and MT and also between TE and IMS server. This prior art primarily addresses the need of terminal equipment with regular SIP UA to communicate with IMS server through IMS proxy adjunct and this scheme is more suited for IMS enabling existing PC or PDA based regular SIP applications. Hence this prior art does not address a solution that implements IMS client functions as a cellular phone accessory. Also, this prior art does not address the issue of enabling IMS services to work with low end and middle range cellular phones.
As can be seen from above, no known prior art shows a device that is both a cellular phone accessory and an IMS client to deliver new real time interactive multimedia applications to mass market without said re-engineering efforts.